In many conventional electrolytic cells, a separator is affixed between anode and cathode within the cell, defining anode and cathode compartments within the electrolytic cell. Generally, differing electrolytes are present in each of these compartments, the electrolytes being generally related to reactions occurring at the particular electrode present in that compartment. For example, in a chlor alkali cell, an alkali metal chloride salt brine electrolyte is present in the anode compartment as an anolyte, and a solution of hydroxide of the alkali metal is present in the cathode compartment as a catholyte. Depending upon the hydraulic permeability of the separator, the catholyte can also include quantities of the alkali metal chloride salt.
In such chlor alkali cells, chlorine generally is evolved from the brine at the anode, while, in many cells, hydrogen gas is evolved at the cathode resulting from the decomposition of water to form hydroxyl groups that react with alkali metal ions crossing the separator in transmitting electrical current between anode and cathode. In one particular type of cell, a so-called oxygen cathode cell, oxygen is present with an electrocatalytic material at the cathode, and the oxygen combines with hydrogen ions being evolved to reform water. The energy associated with forming gaseous H.sub.2 is thereby avoided, resulting in substantial power savings in operation of the cell.
In a typical oxygen cathode type cell, the anode and the oxygen cathode are retained individually within separate frames. These frames separated by the separator generally define anode and cathode compartments for electrolyte retention. Where the separator is a membrane, the membrane is retained between the frames. Where the separator is a porous separator, it may be retained between the frames or separately supported. Where a separator is retained between the frames, it is often separated from the frames by a gasketing material.
In a typical oxygen cathode cell, a sheet like cathode is retained upon the cathode frame. Catholyte contacts one surface of the cathode, with an oxygen containing gas contacting the other surface of the cathode. The oxygen containing gas typically is introduced through passages contained in the cathode frame, and gas depleted in oxygen content similarly removed.
Catholyte typically is introduced and removed through a catholyte feed frame. This catholyte feed frame generally is positioned between the separator and cathode frame, and effectively spaces the cathode and separator one from the other. This spacing contributes to an elevated voltage in operating the cell due to a resistance voltage drop due to electrical current passing through catholyte occupying this spacing within the cell. Could this spacing attributable to the thickness of a cathode feed frame be eliminated or reduced, considerable voltage savings could be achieved in the operation of the electrochemical cell.